Exposure of mice to long-light: A new animal model to study depression

Mood disorders are highly prevalent and often difficult to treat. One of the most important obstacles in research on depression is the limited availability of reliable and valid animal models. Here we demonstrate that the exposure of mice to artificial daylight for 22 h per day produces a spectrum of behavioral and endocrine symptoms reminiscent to those seen in animal models of depression. Oral administration of the antidepressant imipramine has strong impact on these symptoms. Our results indicate that long-light exposure of mice represents a simple new method to study depression.